A large numver of different systems for automatic sorting of cutlery after machine washing in large kitchens have been suggested. With systems already known the cutlery has for example been sorted by weight as per U.S. Pat. Nos. 3,331,507, 3,483,877 and 3,581,750, through mechanical recognition in holes, slots etc., as per U.S. Pat. Nos. 3,301,397, 3,389,790, 3,389,791, 3,545,613 and 3,956,109, or through detection of the cutlery's magnetic properties in electro-magnetic fields as per U.S. Pat. Nos. 3,394,809 and 3,486,939. These weight-recognising, mechanically or electro-magnetically working recognition systems are, however, either complicated, slow, expensive and/or unreliable or have other disadvantages. As far as is known they have therefore not been of any practical significance.
Another known procedure is to detect objects dynamically through optical recognition, as for example through U.S. Pat. No. 3,529,169 and EP-A1-20 108. The systems described in these patent specifications, are, however, unsuitable for sorting of cutlery and suchlike objects.